I. Field of the Invention
The present invention relates to medical devices and, more particularly, to a connector assembly for an implantable medical device.
II. Description of the Related Art
Implantable medical devices are frequently used to generate an electrical stimulus that is transferred to a target tissue. These devices may also be used to sense electrical signals generated from the target tissues or generated by sensors located at a target location. Some examples of such devices include neurostimulation devices, pacemakers, anti-tachycardia pacers, and defibrillators. Neurostimulation devices are frequently used to artificially stimulate nerves to relieve pain and to treat various neurological disorders whereas pacemakers, anti-tachycardia pacers, and defibrillators are used to stimulate cardiac tissue with an electrical signal in order to correct or modify the rhythm of the heart. Implantable devices generally include a housing which typically hermetically encloses a battery and electronic-circuitry for generating and/or sensing electrical signals. The housing can be implanted subcutaneously. A header, or connector top assembly typically electrically connects an implantable electrode to the housing. The header, or connector top assembly typically includes a connector block assembly secured within the header, or connector top assembly. The electrode typically includes one or more exposed contact surfaces at the distal end that make contact with the tissue or nerve that requires stimulation or sensing. The proximal end of the electrode typically includes corresponding contact surfaces that are mechanically and electrically coupled to the medical device by the header, or connector top assembly. This series of contact surfaces along the proximal connector section, electrically connects the electrode to the connector blocks within the header, or connector top assembly. The proximal connector of the electrode is typically received by the connector assembly through one or more ports in the header. Each of these ports may require a single or multiple contact connector block assemblies, depending on the electrode configuration.
Replacing the implanted device requires the removal of the housing from the patient. This replacement is preferably accomplished without disturbing the associated implanted electrodes. Therefore, it is advantageous that the electrode connection is readily disconnectable. To facilitate this, the proximal connector is typically secured within the header, or connector top assembly with a set screw. A set screw contacting the proximal connector pin is commonly used to permit the electrode to be secured to and removed from the header, or connector top assembly. The header, or connector top assembly is secured and electrically connected to the electronics of the housing to permit the communication of electrical impulses to and/or from the electronics within the housing.
Manufacturing connector assemblies is expensive. The connector blocks of the connector assembly are frequently machined from titanium, stainless steel or other more exotic materials. Machining these materials has limitations. One limitation is the amount of detail capable of being machined on the sealing surface of each connector block. Increased detail could permit configurations of the connector block that would allow variations in block design. These variations could simplify the manufacturing process, could improve function and could reduce the costs of manufacture. Therefore, a need exists for a connector assembly that can be manufactured without the need for machining titanium, stainless steel or other more exotic materials.
Frequently, these connector blocks are individually mounted within preformed cavities in the header, or connector top assembly. These preformed cavities frequently have thin walls that are susceptible to damage. Current methods of manufacture frequently require the formation of these cavities in the injection molded header assemblies to receive the connector blocks. Therefore, a need exists for a header, or connector top assembly that does not require the formation of individual preformed cavities to secure the connector blocks.
Further, titanium, stainless steel and more exotic material connector blocks can result in a relatively heavy connector assembly. Heavy assemblies are not desirable. Therefore, a need exists for a connector assembly unencumbered by the extra weight of the titanium, stainless steel and more exotic material connector blocks typically used in the industry.